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showing 10 items of 6745 documents
Discrimination of fish populations using parasites: Random Forests on a ‘predictable’ host-parasite system
2010
SUMMARYWe address the effect of spatial scale and temporal variation on model generality when forming predictive models for fish assignment using a new data mining approach, Random Forests (RF), to variable biological markers (parasite community data). Models were implemented for a fish host-parasite system sampled along the Mediterranean and Atlantic coasts of Spain and were validated using independent datasets. We considered 2 basic classification problems in evaluating the importance of variations in parasite infracommunities for assignment of individual fish to their populations of origin: multiclass (2–5 population models, using 2 seasonal replicates from each of the populations) and 2…
INHIBITION OF THE FUNGAL PATHOGEN METARHIZIUM ANISOPLIAE IN THE ALIMENTARY TRACTS OF FIVE TERMITE (ISOPTERA) SPECIES
2010
We previously showed that in the subterranean termite Reticulitermes flavipes conidia of Metarhizium anisopliae did not germinate in the alimentary tract of living termites and the antifungal activity remained for 2 d post mortem in the gut. We have confirmed that this mechanism is common throughout the termite phylogeny by extending our observations to 5 additional species, from 5 different families. Grooming and ingestion of microorganisms from the cuticle ofnestmate was found to be consistent in all the species and none of the conidia found in the alimentary tracts germinated.
Cellular encapsulation in the eastern subterranean termite, Reticulitermes flavipes (Isoptera), against infection by the entomopathogenic fungus Meta…
2009
Reticulitermes flavipes workers were topically inoculated with approximately 10,000 conidia of the entomopathogenic fungus Metarhizium anisopliae. After being kept in groups of 20 individuals for 1-9 d, histopathological examination showed that termites had an individual immune reaction. The nodule formation at the point of entrance of the fungal hyphae was identified as a cellular encapsulation and the different steps in the nodule formation are described. The relative number of hemocytes per termite increased 24h after fungal exposure and remained high in the hemolymph for at least 3 d before decreasing back to pre-exposure levels. The role of an individual immune cellular reaction in soc…
The phylogeny of termites (Dictyoptera : Isoptera) based on mitochondrial and nuclear markers : implications for the evolution of the worker and pseu…
2008
A phylogenetic hypothesis of termite relationships was inferred from DNA sequence data. Seven gene fragments (12S rDNA, 16S rDNA, 18S rDNA, 28S rDNA, cytochrome oxidase I, cytochrome oxidase II and cytochrome b) were sequenced for 40 termite exemplars, representing all termite families and 14 outgroups. Termites were found to be monophyletic with Mastotermes darwiniensis (Mastotermitidae) as sister group to the remainder of the termites. In this remainder, the family Kalotermitidae was sister group to other families. The families Kalotermitidae, Hodotermitidae and Termitidae were retrieved as monophyletic whereas the Termopsidae and Rhinotermitidae appeared paraphyletic. All of these result…
Bayesian analysis improves experimental studies about temporal patterning of aggression in fish.
2017
Made available in DSpace on 2018-12-11T17:15:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-12-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) This study aims to describe a Bayesian Hierarchical Linear Model (HLM) approach for longitudinal designs in fish's experimental aggressive behavior studies as an alternative to classical methods In particular, we discuss the advantages of Bayesian analysis in dealing with combined variables, non-statistically significant results and required sample size using an experiment of angelfish (Pterophyllum scalare) species as case study. Groups of 3 individuals were subjected to daily observations recorded for 10 min durin…
Going underground: short- and long-term movements may reveal the fossorial spatial ecology of an amphisbaenian
2021
[Background]: The movement and spatial ecology of an animal depends on its morphological and functional adaptations to its environment. In fossorial animals, adaptations to the underground life help to face peculiar ecological challenges, very different from those of epigeal species, but may constrain their movement ability.
ILTER – The International Long-Term Ecological Research Network as a Platform for Global Coastal and Ocean Observation
2019
International audience; Understanding the threats to global biodiversity and ecosystem services posed by human impacts on coastal and marine environments requires the establishment and maintenance of ecological observatories that integrate the biological, physical, geological, and biogeochemical aspects of ecosystems. This is crucial to provide scientists and stakeholders with the support and knowledge necessary to quantify environmental change and its impact on the sustainable use of the seas and coasts. In this paper, we explore the potential for the coastal and marine components of the International Long-Term Ecological Research Network (ILTER) to fill this need for integrated global obs…
Ecdysone and ecdysterone in physogastric termite queens and eggs of Macrotermes bellicosus and Macrotermes subhyalinus
1978
Abstract Physogastric queens and freshly laid eggs of two species of termites ( Macrotermes bellicosus and Macrotermes subhyalinus ) are found to contain high levels of ecdysteroids (molting hormones) as indicated by radioimmunoassay and Musca bioassay. Ecdysteroids are accumulated in the ovaries of the queen and then stored in the eggs since newly laid eggs contain ecdysteroid concentrations similar to those found in the ovaries. Gas chromatography-mass spectrometry demonstrates that ecdysone (α-ecdysone) as well as ecdysterone (β-ecdysone) are present in queen ovaries and in eggs and that ecdysone is quantitatively the more important ecdysteroid in both ovary and eggs.
The mechanistic basis of changes in community assembly in relation to anthropogenic disturbance and productivity
2016
Anthropogenic disturbance often causes changes in communities. However, the mechanistic basis of these changes remains elusive. As all patterns in community ecology can be understood as a result of four processes (speciation, selection, drift, and dispersal), the effect of disturbance should depend on how disturbance disrupt these processes. We studied the effects of disturbance and productivity on species richness, community composition, and community dispersion (i.e., variation in community composition) in the vegetation of 120 boreal peatlands using null-model approach to determine whether community assembly processes differ between pristine and disturbed sites. Sites represented three p…
An Empirical Evaluation of the Utility of Convex Hull and Standard Ellipse Areas for Assessing Population Niche Widths from Stable Isotope Data
2013
Stable isotope analyses are increasingly employed to characterise population niche widths. The convex hull area (TA) in a δ¹³C–δ¹⁵N biplot has been used as a measure of isotopic niche width, but concerns exist over its dependence on sample size and associated difficulties in among-population comparisons. Recently a more robust method was proposed for estimating and comparing isotopic niche widths using standard ellipse areas (SEA), but this approach has yet to be tested with empirical stable isotope data. The two methods measure different kind of isotopic niche areas, but both are now widely used to characterise isotopic niche widths of populations. We used simulated data and an extensive e…